Spatial Distribution of Adults and Nymphs of Euschistus heros (F.) (Hemiptera: Pentatomidae) on Bt and Non-Bt Soybean

Abstract

The knowledge of the arrangements of dispersion of insect pests in soybean cultivars is needed to improve the monitoring and control. The objective of this study was to evaluate the spatial distribution of adults and nymphs of Euschistus heros in Bt and non-Bt soybean into two regions, under field conditions. The experimental area located in Dourados and Douradina, Mato Grosso do Sul. For the evaluations we used the method of cloth-to-beat, where we collected one sample per plot randomly from each experimental area. Evaluations were performed at 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98 days after emergence (DAE). For data analysis, the rates of dispersion (variance/average Morisita index and exponent k  Negative Binomial Distribution) and theoretical frequency distributions (Poisson, Binomial and Negative Binomial Positive) were estimated at 1-5 % probability. Adults of E. heros are arranged differently for Bt and non-Bt soybean and between regions, since in both cultivars and locations, individuals of the populations evaluated in probabilistic set arrangements negative binomial distribution (aggregate), Poisson (random) and positive binomial distribution (uniform), as the days after soybean emergence. The nymphs of E. heros showed aggregated spatial arrangement, being distributed similarly for Bt and non-Bt soybean and regions, setting a negative binomial distribution model.

Spatial distribution of nymphs and adults of Euschistus heros (Fabricius, 1794) (Heteroptera: Pentatomidae) in transgenic soybean cultivars of different maturing cycles

“…The results obtained in the present work corroborate those found by Fonseca et al (2014) who studied the dispersion of E. heros in an intact Bt soybean cultivar that expressed the Cry1Ac protein as well as in a non-Bt soybean that was resistant to the herbicide glyphosate. In that case, the authors reported that the nymphs had an aggregated spatial pattern that best fits a negative binomial distribution.…”

“…Fonseca et al (2014), in a study performed at two locations in the state of Mato Grosso do Sul, Brazil, confirmed that E. heros nymphs showed an aggregated spatial pattern, which best fits the negative binomial distribution, in both Bt soybean and non Bt soybean cultivars. Regarding adults, the dispersion pattern varied from aggregated to uniform, according to the stage of development of the crop.…”

Sequential Sampling of Adults and Nymphs of Euschistus heros (F) (Hemiptera: Pentatomidae) on Soybean Bt and Non-Bt

“…To construct the sequential sampling plan for the number of adults and nymphs of E. heros, settled by adhesion test frequency that the Negative Binomial distribution is the model that describes the type of spatial distribution in the field with greater precision, according to the results obtained by Fonseca et al (2014). The adopted control level of 2.0 bugs per cloth-to-beat (adults and nymphs).…”

“…Taking into account also that the soybean crop and cultivated in areas with large tracts, the sampling is fundamental to locate the presence of this pest in different locations of a property that already exists population dynamics of the same environment, as well as in different environments (Fonseca et al, 2014). Population dynamics and influenced by climatic conditions (rainfall, temperature) which is necessary to achieve constant sampling information accurately.…”

“…The data on the number of adults and nymphs were used for the mathematical description of the spatial dispersion of the population of this insect, which showed adequate fit to the Negative Binomial distribution (Fonseca et al, 2014).…”